Rollup merge of rust-lang#64198 - cramertj:fuchsia-monotonic, r=alexcrichton

Add Fuchsia to actually_monotonic

Fuchsia provides a fully monotonic clock.

Fix rust-lang#64196

cc @joshlf @tmandry

r? @alexcrichton

Author: Centril

src/libstd/sys/unix/time.rs

@@ -311,6 +311,7 @@ mod inner {
         pub fn actually_monotonic() -> bool {
             (cfg!(target_os = "linux") && cfg!(target_arch = "x86_64")) ||
             (cfg!(target_os = "linux") && cfg!(target_arch = "x86")) ||
+            cfg!(target_os = "fuchsia") ||
             false // last clause, used so `||` is always trailing above
         }